From 6b033bc41952dc323b57aa6a5b66069f8bc37d02 Mon Sep 17 00:00:00 2001 Message-Id: <6b033bc41952dc323b57aa6a5b66069f8bc37d02.1715688935.git.mdw@distorted.org.uk> From: Mark Wooding Date: Tue, 1 Jun 1999 09:46:19 +0000 Subject: [PATCH] New addition: bit manipulation macros. Organization: Straylight/Edgeware From: mdw --- bits.h | 150 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 bits.h diff --git a/bits.h b/bits.h new file mode 100644 index 0000000..9d7c6d0 --- /dev/null +++ b/bits.h @@ -0,0 +1,150 @@ +/* -*-c-*- + * + * $Id: bits.h,v 1.1 1999/06/01 09:46:19 mdw Exp $ + * + * Portable bit-level manipulation macros + * + * (c) 1998 Straylight/Edgeware + */ + +/*----- Licensing notice --------------------------------------------------* + * + * This file is part of the mLib utilities library. + * + * mLib is free software; you can redistribute it and/or modify + * it under the terms of the GNU Library General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or (at your option) any later version. + * + * mLib is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with mLib; if not, write to the Free + * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, + * MA 02111-1307, USA. + */ + +/*----- Revision history --------------------------------------------------* + * + * $Log: bits.h,v $ + * Revision 1.1 1999/06/01 09:46:19 mdw + * New addition: bit manipulation macros. + * + */ + +#ifndef BITS_H +#define BITS_H + +#ifdef __cplusplus + extern "C" { +#endif + +/*----- Header files ------------------------------------------------------*/ + +#include +#include + +/*----- Decide on some types ----------------------------------------------*/ + +/* --- Decide on a 32-bit type --- * + * + * I want a type which is capable of expressing 32-bit numbers. Because some + * implementations have 64-bit @long@s (infinitely preferable to the abortion + * that is @long long@), using @unsigned long@ regardless is wasteful. So, + * if @int@ appears to be good enough, then I'll go with that. + */ + +#if UINT_MAX >= 0xffffffffu + typedef unsigned int uint32; +#else + typedef unsigned long uint32; +#endif + +/* --- Decide on 16-bit and 8-bit types --- * + * + * This is more for brevity than anything else. + */ + +typedef unsigned short uint16; +typedef unsigned char octet; + +/* --- WARNING! --- * + * + * Never lose sight of the fact that the above types may be wider than the + * names suggest. Some architectures have 32-bit @short@s for example. + */ + +/*----- Macros ------------------------------------------------------------*/ + +/* --- Useful masks --- */ + +#define MASK8 0xffu +#define MASK16 0xffffu +#define MASK32 0xffffffffu + +/* --- Type coercions --- */ + +#define U8(x) ((octet)((x) & MASK8)) +#define U16(x) ((uint16)((x) & MASK16)) +#define U32(x) ((uint32)((x) & MASK32)) + +/* --- Safe shifting macros --- */ + +#define LSL8(v, s) (U8(v) << ((s) & 7u)) +#define LSR8(v, s) (U8(v) >> ((s) & 7u)) +#define LSL16(v, s) (U16(v) << ((s) & 15u)) +#define LSR16(v, s) (U16(v) >> ((s) & 15u)) +#define LSL32(v, s) (U32(v) << ((s) & 31u)) +#define LSR32(v, s) (U32(v) >> ((s) & 31u)) + +/* --- Rotation macros --- */ + +#define ROL8(v, s) (LSL8((v), (s)) | (LSR8((v), 8 - (s)))) +#define ROR8(v, s) (LSR8((v), (s)) | (LSL8((v), 8 - (s)))) +#define ROL16(v, s) (LSL16((v), (s)) | (LSR16((v), 16 - (s)))) +#define ROR16(v, s) (LSR16((v), (s)) | (LSL16((v), 16 - (s)))) +#define ROL32(v, s) (LSL32((v), (s)) | (LSR32((v), 32 - (s)))) +#define ROR32(v, s) (LSR32((v), (s)) | (LSL32((v), 32 - (s)))) + +/* --- Storage and retrieval --- */ + +#define GETBYTE(p, o) (((octet *)(p))[o] & MASK8) +#define PUTBYTE(p, o, v) (((octet *)(p))[o] = U8((v))) + +#define LOAD8(p) (GETBYTE((p), 0)) +#define STORE8(p, v) (PUTBYTE((p), 0, (v))) + +#define LOAD16_B(p) ((GETBYTE((p), 0) << 8) | GETBYTE((p), 1)) +#define LOAD16_L(p) (GETBYTE((p), 0) | (GETBYTE((p), 1) << 8)) +#define LOAD16(p) LOAD16_B((p)) + +#define STORE16_B(p, v) (PUTBYTE((p), 0, (v) >> 8), PUTBYTE((p), 1, (v))) +#define STORE16_L(p, v) (PUTBYTE((p), 0, (v)), PUTBYTE((p), 1, (v) >> 8)) +#define STORE16(p, v) STORE16_B((p), (v)) + +#define LOAD32_B(p) \ + ((GETBYTE((p), 0) << 24) | (GETBYTE((p), 1) << 16) | \ + (GETBYTE((p), 2) << 8) | (GETBYTE((p), 3) << 0)) +#define LOAD32_L(p) \ + ((GETBYTE((p), 0) << 0) | (GETBYTE((p), 1) << 8) | \ + (GETBYTE((p), 2) << 16) | (GETBYTE((p), 3) << 24)) +#define LOAD32(p) LOAD32_B((p)) + +#define STORE32_B(p, v) \ + (PUTBYTE((p), 0, (v) >> 24), PUTBYTE((p), 1, (v) >> 16), \ + PUTBYTE((p), 2, (v) >> 8), PUTBYTE((p), 3, (v) >> 0)) +#define STORE32_L(p, v) \ + (PUTBYTE((p), 0, (v) >> 0), PUTBYTE((p), 1, (v) >> 8), \ + PUTBYTE((p), 2, (v) >> 16), PUTBYTE((p), 3, (v) >> 24)) +#define STORE32(p, v) STORE32_B((p), (v)) + +/*----- That's all, folks -------------------------------------------------*/ + +#ifdef __cplusplus + } +#endif + +#endif -- [mdw]